System for cutterbar support having torsion device with elastic material and load limiting apparatus

ABSTRACT

A system for supporting a cutterbar of a crop harvesting header includes a first arm pivotably secured to the header. The first arm includes a first portion configured to support the cutterbar. The first arm includes a second portion including a torsion device having a mass of elastic material connected to an adjustment assembly. The second portion is configured to be pivotably rotatable about an axis by the adjustment assembly to selectably increase or decrease a force appliable to the first portion in order to raise or lower the first portion with respect to the header. A load limiting apparatus limits an amount of torsional force that is applied to the mass of elastic material by pivotable rotation of the second portion about the axis.

FIELD OF THE INVENTION

The present invention relates generally to crop harvesting headers foruse with crop harvesting devices. It relates more particularly to asystem for supporting a cutterbar of a crop harvesting header.

BACKGROUND OF THE INVENTION

The cutting assemblies of the known large headers of plant-cuttingmachines (e.g., combine, windrower) are typically driven by anoscillating drive, which can include, but is not limited to, aneccentric shaft on a rotating hub, a wobble drive, or a similarwell-known commercially-available device. A cutting assembly istypically supported by a flexible cutterbar that spans the width of theopening of the crop harvesting header. The cutterbar is typicallysupported by arms that extend transverse to the cutterbar.Unfortunately, the weight of the cutting assembly is not uniformlydistributed across the cutting width of the harvesting header, possiblycausing bowing of the cutterbar, and the cutting assembly, resulting inuneven cutting height of the plant, as well as other undesirableresults.

In response, Applicant has made great strides in this area through theuse of a torsion device having elastic material, such as disclosed inU.S. Pat. No. 8,051,633, titled Cutterbar Adjustment Support For AHarvesting Header. However, further improvements are needed, such asmaintaining performance while extending the service life of the elasticmaterial.

What is needed is a system that provides substantially uniform supportalong the length of the cutting assembly by permitting selectiveadjustment of the forces the arms provide to the cutterbar, whilemaintaining performance and extending the service life of the system.

SUMMARY OF THE INVENTION

The present invention relates to a system for supporting a cutterbar ofa crop harvesting header including a first arm pivotably secured to theheader. The first arm includes a first portion configured to support thecutterbar, the first arm including a second portion including a torsiondevice having a mass of elastic material connected to an adjustmentassembly. The second portion is configured to be pivotably rotatableabout an axis by the adjustment assembly to selectably increase ordecrease a force appliable to the first portion in order to raise orlower the first portion with respect to the header. A load limitingapparatus is operatively connected to the torsion device for limiting anamount of torsional force that is applied to the mass of elasticmaterial by pivotable rotation of the second portion about the axis. Theadjustment assembly includes a second arm interconnecting the torsiondevice and an adjustment device having a first segment, the adjustmentdevice configured to movably receive a connecting adjustment device. Thefirst segment of the adjustment device is configured to follow apredetermined path in a first direction with respect to the axis inresponse to movement of the adjustment device in a first direction withrespect to the first adjustment device. The first segment of theadjustment device is configured to follow a predetermined path in asecond direction with respect to the axis in response to movement of theconnecting adjustment device in a second direction opposite the firstdirection with respect to the adjustment device.

The present invention further relates to a system for supporting acutterbar of a crop harvesting header including a first arm pivotablysecured to the header. The first arm includes a first portion configuredto support the cutterbar, the first arm including a second portionincluding a torsion device having a mass of elastic material connectedto an adjustment assembly, the second portion configured to be pivotablyrotatable about an axis by the adjustment assembly to selectablyincrease or decrease a force appliable to the first portion in order toraise or lower the first portion with respect to the header. A loadlimiting apparatus is operatively connected to and contained inside thetorsion device for limiting an amount of torsional force that is appliedto the mass of elastic material by pivotable rotation of the secondportion about the axis. The adjustment assembly includes a second arminterconnecting the torsion device and an adjustment device having afirst segment, the adjustment device configured to movably receive aconnecting adjustment device. The first segment of the adjustment deviceis configured to follow a predetermined path in a first direction withrespect to the axis in response to movement of the adjustment device ina first direction with respect to the first adjustment device. The firstsegment of the adjustment device is configured to follow a predeterminedpath in a second direction with respect to the axis in response tomovement of the connecting adjustment device in a second directionopposite the first direction with respect to the adjustment device.

An advantage of the present invention is a system applying asubstantially uniform support force for the cutterbar, while maintainingperformance and extending the service life of the system.

Other features and advantages of the present invention will be apparentfrom the following more detailed description of the preferredembodiment, taken in conjunction with the accompanying drawings whichillustrate, by way of example, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of an embodiment of a crop harvesting device andharvesting header of the present invention.

FIG. 2 is a top perspective view of the crop harvesting device of FIG. 1of the present invention.

FIG. 3 is a cross section taken along line 3-3 of the present invention.

FIG. 4 is an exploded view of a cutterbar support arm of the presentinvention.

FIG. 5 is a forward-looking end view of an adjustment device of thepresent invention.

FIG. 6 is an enlarged end view of a torsion device of the presentinvention.

FIG. 7 is a cross section taken along line 7-7 from FIG. 6 of thepresent invention.

FIGS. 8-9 are enlarged top perspective views of the adjustment device ofFIG. 5 shown in different rotational positions of the present invention.

FIG. 10 a cross section taken along line 10-10 of the adjustment deviceof FIG. 5 of the present invention.

FIGS. 11-12 are embodiments of a second adjustment device of the presentinvention.

FIG. 13 shows a perspective view of an embodiment of a torsion device ofthe present invention.

FIG. 14 shows an end view of an embodiment of a torsion device of thepresent invention.

Wherever possible, the same reference numbers will be used throughoutthe drawings to refer to the same or like parts.

DETAILED DESCRIPTION OF THE INVENTION

A combine 20, which is a well-known agricultural cutting and harvestingmachine, is shown in FIG. 1. Combine 20 includes a header 22, which isconfigured to cut or sever crops, including (without limitation) smallgrains (e.g., wheat, soybeans), and to induct the cut or severed cropsinto a feeder 26. Both functions can be performed as combine 20 movesforward over a crop field.

Header 22 is attached to a forward end 24 of combine 20 and includes apan or floor 28 that is supported in desired proximity to the surface ofa crop field. Header 22 includes an elongated sidewardly extendingsickle 30 along a forward edge portion 32 (see FIG. 2) of floor 28. Acutter or sickle 30 is configured to cut or sever crops, in preparationfor induction into a feeder 26. Additionally, header 22 may include anelongate, sidewardly extending reel 34 disposed above sickle 30. Reel 34is rotatable in a direction suitable for facilitating the induction ofcut or severed crops into feeder 26. Header 22 further includes anelongate, rotatable auger 36, which extends in close proximity to a topsurface 38 of floor 28 and has helical flights therearound. Auger 36 isconfigured to cooperate with reel 34 in conveying cut or severed cropsto feeder 26, which is configured to convey the cut or severed cropsinto combine 20 for threshing and cleaning. Alternatively, instead ofrotatable auger 36, header 22 may include a draper header or other cropharvesting/gathering header.

Sickle 30 extends along a forward edge 40 of floor 28, and generally isbounded by a first side edge 42 and an opposing second side edge 44,both of floor 28. Sickle 30 is supported by a cutterbar 45 (see FIG. 3)which is likewise supported by a first portion 46 of an elongated memberor first arm 48 that will be discussed in further detail below. Duringoperation, sickle 30 reciprocates rapidly to effect a cutting orsevering action that cuts or severs plant stems, stalks or othermaterial present between the blades of the sickle. As denoted by arrow50, the sickle blades can reciprocate sideways.

As shown in FIGS. 3-5, a C-bracket or second portion 52 of member orfirst arm 48 is pivotably secured to header 22 about an axis 56 by a rod58 having a non-circular periphery, such as a hexagonal periphery. Rod58 further extends through openings formed in plates 94, 96 that aresecured to header 22 and laterally surround second portion 52. In otherwords, rod 58 extends through each of plates 94, 96, apertures 98 formedin second portion 52 and a torsion device 90 forming part of a cutterbarsupport system 300. That is, fasteners 104 are first inserted throughrespective aligned openings 106 in second portion 52 and aperturesformed in torsion device 90 to secure the torsion device to the secondportion (assembling the exploded view of FIG. 4). Once the torsiondevice 90 is assembled to the second portion 52, aperture 98 of secondportion 52 is positioned between and aligned with openings (not shown)formed in plates 94, 96 and their respective bushings 100, rod 58 maythen be inserted through plates 94, 96, bushings 100, second portion 52and torsion device 90 (see FIG. 5). After insertion of rod 58, the outerperiphery of rod 58 and an inside surface 80 (see FIG. 4) of torsiondevice 90 are placed in a non-rotating relationship, i.e., they becomemated surfaces. Finally, opening 108 (see FIG. 8) of second arm 102 isaligned and slid over rod 58, with opening 108 and rod 58 definingmating surfaces and fastener 110 installed in rod 58 to secure rod 58 inits installed position. At this point, in response to first arm 48 beingurged into rotational movement about axis 56, by virtue of the matingsurfaces between rod 58 and inside surface 80 of torsion device 90 andbetween opening 108 of second arm 102 and rod 58, rod 58 and second arm102 would each be urged into rotation about axis 56.

Other operating details may be contained in U.S. Pat. No. 8,051,633,titled Cutterbar Adjustment Support For A Harvesting Header, which isincorporated by reference in its entirety.

FIGS. 6-7 show a side view and a cross section, respectively, of torsiondevice 90. Torsion device 90 includes a housing 60 includes a pluralityof lobes 64 having corresponding apertures 62 formed in the lobes,permitting the housing to be secured to other structure, such as plate94, 96 (FIG. 5) by mechanical fasteners 104 extending through the otherstructure and apertures 62. Housing 60 includes an inside surface 66that may include a tapered surface 82, such as shown in FIG. 7. A member68, which includes an inside surface 70 and an outside surface 72, iscomprised of a resilient material mass that is inserted inside ofhousing 60. In one embodiment, member 68 is composed of a non-metal,such as a rubber material. Inside surface 66 of housing 60 is configuredto receive outside surface 72 of member 68 and define a substantiallynon-rotational contact therebetween. Stated another way, subsequent toinsertion of member 68 inside of housing 60, in response to a rotationalmovement 86 applied in a clockwise direction about axis 56 to housing 60and an opposed rotational movement 88 applied in a counter clockwisedirection about axis 56 to member 68, inside surface 66 and outsidesurface 72 should not rotatably move with respect to each other. Suchnon-rotational contact may be established by application of adhesives,interference-fit (due to the periphery of inside surface 66 being largerthan the periphery of outside surface 72), mating surface features, suchas splines, or the like.

As further shown in FIGS. 6-7, inside surface 70 of member 68 isconfigured to receive a sleeve 76 having an outside surface 78 andinside surface 80. Housing 60 and sleeve 76 are composed ofsubstantially rigid materials, such as metals. When member 68 and sleeve76 are assembled together, inside surface 70 of the member and outsidesurface 78 of the sleeve define a substantially non-rotational contacttherebetween, as discussed above. Inside surface 80 of sleeve 76 definesa geometric shape that is configured to receive an object, such as ashaft, in a substantially non-rotational contact. As shown in FIG. 6,inside surface 80 defines a hexagonal profile, although other profilesmay be used. In a further embodiment, sleeve 76 may not be required, ifinside surface 70 of member 68 defines a hexagonal profile, for example.

As shown in FIG. 7, member 68 includes recessed ends 74. In oneembodiment, recessed ends 74 may be created during the normal coolingprocess of member 68, which may be composed of rubber or anothersuitable resilient material. That is, member 68 may be heated to aliquid state and then installed while in the liquid state, such as bypouring or injection molding, into housing 60 between inside surface 70and outside surface 72. During cooling, member 68 bonds to each ofinside surface 70 and outside surface 72. In an alternate embodiment,member 68 may be press-fit between inside surface 70 and outside surface72. In yet another embodiment, member 68 may be secured between insidesurface 70 and outside surface 72 by use of an adhesive.

In summary, by virtue of the collective substantially non-rotationalcontacts established between corresponding surfaces of housing 60,member 68, sleeve 76 and a shaft received by the sleeve, in response toa rotational movement 86 about axis 56 applied by a shaft 58, and acounter rotational movement 88 about axis 56 applied to oppose therotational movement applied by the shaft, the member 68 is subjected toa torsional force, which is the basis for the equalizing torsional forceprovided by the support system.

Referring to FIGS. 3, 5, and 8-10, adjustment assembly 92 is nowdiscussed. Adjustment assembly 92 includes second arm 102 having anaperture 114 located distantly from opening 108 that is pivotablyconnected, such as by fastener 118 to a first segment 116 of a firstadjustment device 112. In one embodiment, first segment 116 includes aneyelet (see FIG. 3) formed in first adjustment device 112, with thefirst adjustment device being a threaded rod. First adjustment device112 is movably connected with a second adjustment device 120. In oneembodiment, the second adjustment device is a threaded nut configured tomate with the first adjustment device. After assembly, second adjustmentdevice 120 is placed in abutting contact with the portion of header 22.In one embodiment, the portion of header 22 is a bracket 122, in whichthe abutting contact occurs between a portion of the exterior surface ofsecond adjustment device 120 and at least a portion of a surface of anaperture 124. In one embodiment, at least a portion of second adjustmentdevice 120 includes a tapered surface 126. In one embodiment, taperedsurface 126 is curved. Tapered surface 126 is configured to increase theamount of surface area of the abutting contact between the surface ofaperture 124 of bracket 122, thereby reducing the amount of resistancerequired to move second adjustment device 120 with respect to bracket122. In a further embodiment, the abutting contact surfaces betweentapered surface 126 and aperture 124 define conformal surfaces. That is,the abutting contact surfaces substantially conform with each other tomaximize the amount of shared surface area to reduce the amount ofresistance between the contact surfaces in response to a given forcedirected perpendicular to the contact surfaces. To urge rotationalmovement of second adjustment device 120 with respect to bracket 122, aregion 128 is provided to receive a tool, such as a wrench, or inanother embodiment, the region defines an opening to receive a leverarm.

By virtue of adjustment assembly 92, such as shown in the FIG. 3, firstportion 46 of first arm 48 can be selectively raised or lowered. Inother words, in response to a rotational movement in a first rotationaldirection or a first tendency of second adjustment device 120, secondadjustment device 120 is placed in abutting contact with bracket 122such that the length of first adjustment device 112 between bracket 122and first segment or eyelet 116 is increased, urging second arm 102 torotate about axis 56. When sufficient rotation of second arm 102 hasoccurred, and has applied a sufficient torsional force to torsion device90, first portion 46 of first arm 48 is raised with respect to header 22subject to the header encountering a stop 132 extending from the firstarm. Stop 132 may also be employed to limit the lowest position of firstportion 46 with respect to header 22. Conversely, in response to arotational movement in a second rotational direction or a secondtendency of second adjustment device 120, second adjustment device 120is placed in abutting contact with bracket 122 such that the length offirst adjustment device 112 between bracket 122 and first segment oreyelet 116 is decreased, urging second arm 102 to rotate about axis 56.When sufficient rotation of second arm 102 has occurred, and has applieda sufficient torsional force to torsion device 90, first portion 46 offirst arm 48 is lowered with respect to header 22. Depending upon theapplication, multiple first arms 48 may be used to provide support forthe cutterbar.

It is also to be understood that while adjustment assembly 92 may beused to selectively raise or lower first portion 46 of first arm 48, thesame techniques and interaction between components previously discussedmay also be used to selectively increase or decrease a force that may beapplied to first portion 46 of first arm 48 in order to raise or lowerfirst portion with respect to header 22. That is, for example, stop 132extending from first arm 48 may be in abutting contact (not shown) withheader 22 such that first arm 48 cannot be further lowered with respectto header 22. For purposes of discussion only, and not intending to belimiting, a force of X pounds may be required to raise first portion 46with respect to header 22. By moving second adjustment device 120 in afirst tendency, without raising/lowering first portion 46 with respectto header 22, a force of Y pounds (Y<X) may then be required to raisefirst portion 46 with respect to header 22. Conversely, by moving secondadjustment device 120 in a second tendency, instead of a first tendency,also without raising/lowering first portion 46 with respect to header22, a force of Z pounds (Z>X) may then be required to raise firstportion 46 with respect to header 22. In other words, for purposes ofcomparison only, X, Y and Z correspond to magnitudes of forces eachbeing applied in the same direction with respect to the header in orderto raise or lower the header. In one embodiment, the magnitude of forcerequired to raise or lower the first portion of each first arm would bethe same.

By virtue of the arrangement of adjustment assembly 92, due to firstadjustment device 112 being located between second arm 102 and secondadjustment device 120, during operation of the adjustment assembly,first segment or eyelet 116 of first adjustment device 112 is configuredto follow a predetermined path with respect to axis 56. In the exemplaryembodiment as shown in FIG. 10, a predetermined path of first segment oreyelet 116 corresponds to the radius defined by axis 56 and aperture 114of second arm 102. As a result of this arrangement, over the operatingrange of adjustment assembly 92, bending forces that could otherwise beapplied to first adjustment device and cause damage to the firstadjustment device are virtually eliminated. That is, by virtue of themovable abutting contact between tapered surface 126 and the surface ofaperture 124 of bracket 122 over the operating range of angular movementof second arm 102 about axis 56, including different positions as shownin respective FIGS. 8 and 9 and as shown in FIG. 10 by a centerlinerepresentation 130 of first adjustment device 112, first adjustmentdevice 112 can pivot with virtually no lateral forces associated withthe abutting contact.

Referring to FIGS. 11 and 12, alternative embodiments of secondadjustment device 220, 320 are shown, in which opposed tapered surfacesare combined into a single component. For second adjustment device 220,the larger ends of the tapered surfaces face each other, which wouldnormally require removal of the second adjustment device from the matingfirst adjustment device if the rotational direction or tendency were tobe reverse. For second adjustment device 320, the smaller ends of thetapered surfaces face each other, which should not require removal ofthe second adjustment device from the mating first adjustment device ifthe rotational direction or tendency were to be reversed. However, theaperture 124 of bracket 122 would need to be “opened up” to form a slotin order to receive second adjustment device 320. Adjustment regions 128configured to receive tools could be located as shown or in otherlocations.

As will be shown in an exemplary embodiment below, a load limitingapparatus, such as load limiting apparatus 394 (FIG. 14) may be utilizedwith a cutterbar support system. The load limiting apparatus is providedin order to limit the extent of torsional flexure of elastic orresilient member 68 operatively connected to torsion device 90 as aresult of forces generated by adjustment assembly 92 in order to raiseor lower cutterbar 45 as previously discussed. FIG. 3 shows cutterbar 45in a raised position 178 versus a lowered position 180. Raised position178 corresponds to stop 132 being positioned at an upper extent of aslot 184 formed in bracket 182 of frame 22. Lowered position 180corresponds to stop 132 being positioned at a lower extent of slot 184formed in bracket 182 of frame 22. The different positions may be usedfor different kinds of crops. For example, raised position 178 isgenerally the preferred position for harvesting wheat, while loweredposition 180 is generally the preferred position for harvestingsoybeans. Prior to utilization of a load limiting apparatus, such asload limiting apparatus 394, which will be discussed in further detailbelow, in order to raise cutterbar 45 from its lowered position 180 toraised position 178, it had been required to subject elastic orresilient member 68 of torsion device 90 to the entire torsional loadgenerated by the downward force applied by first adjustment device 112and second arm 102 about axis 56. This extended load resulted in areduction in performance and service life.

That is, while permitting support and the normal range of movement ofcutterbar 45 about axis 56 between lowered position 180 and raisedposition 178, the positions corresponding to appropriate positions forcutting different types of crops, the load limiting apparatus preventsfurther rotational movement of elastic or resilient material 68 relativeto housing 60 (FIG. 6), thereby limiting the extent of torsional flexureof elastic or resilient member 68. This limitation of rotationalmovement provides several benefits including, substantially preventingdamage to elastic or resilient member 68 associated with such excessiverotational movement of the resilient member relative to its housing, aswell as substantially preventing premature loss of structuralperformance of elastic or resilient member 68, sometimes referred to as“spring characteristics”. In addition, the load limiting device mayprovide structural support of the cutterbar components in some instancesor positions, including a reduction or removal of torsional loadsnormally applied to the resilient material. By reducing or removingtorsional loads applied to the resilient material when possible byvirtue of the load limiting apparatus, service life, sometimes referredto as fatigue life of the resilient material, as well as the timeduration at which high levels of structural performance can bemaintained, may be significantly improved.

As shown collectively in FIGS. 13-14, an exemplary embodiment of torsiondevice 390 includes a load limiting apparatus 394 contained inside orsubstantially inside of torsion device 390. Torsion device 390 includesa housing 360 having an inside surface 366 that is configured torotatably receive an inner hub 350 having an outside surface 348. Aclearance 342 is provided between inside surface 366 and outside surface348 to permit inner hub 350 to rotate about an axis 56 relative tohousing 360. Inner hub 350 and housing 360 have respective abuttingfeatures 346, 344 to limit rotation relative to one another in at leastone rotational direction about axis 56. As further shown in FIG. 14,abutting feature 346, 344 defines a tooth in each of respective innerhub 350 and housing 360. As shown FIG. 14, a rotational movement range338 is provided between corresponding abutting features 346, 344, whichis sized to permit an amount of relative rotational movement ofrespective inner hub 350 relative to housing 360 prior to achievingabutting contact between the corresponding abutting features 346, 344.As shown in FIG. 14, sufficient rotational movement in a clockwiserotational direction, such as by rod 58 (not shown) which is configuredto be received by inside surface 336 of inner hub 350, achieves abuttingcontact between abutting features 346, 344. Upon achieving abuttingcontact between abutting features 346, 344, additional rotationalmovement in a clockwise rotational direction such as by rod 58 resultsin inner hub 350 and housing 360 rotating in unison, acting as a singlemechanical assembly.

That is, as shown collectively in FIGS. 13-14, rotational movement range338 provided between corresponding abutting features 346, 344 permitsrelative rotational movement of respective inner hub 350 in a clockwisedirection relative to housing 360, and therefore results in an amount oftorsional flexure of elastic or resilient member 68 prior to achievingabutting contact between the corresponding abutting features 346, 344.However, once abutting contact between corresponding abutting features346, 344 is achieved, further rotation of inner hub 350 in a clockwisedirection relative to housing 360 results in inner hub 350 and housing360 rotating in unison. Prevention of further relative rotation of innerhub 350 in the clockwise direction relative to housing 360 likewiseprevents further torsional loading of resilient or elastic member 68.The amount of rotational movement range 338 provided betweencorresponding abutting features 346, 344 can be sized such that theamount of torsional flexure of elastic or resilient member 68 achievedcan range anywhere between zero and an amount sufficient to raise thecutterbar. In other words, one having ordinary skill in the artappreciates that in the arrangement described, torsional flexure ofelastic or resilient member 68 has the effect of reducing the amount offorce associated with raising first portion 46, and therefore, thecutterbar (FIG. 3). In one embodiment, the amount of torsional flexureof elastic or resilient member 68 (associated with an amount ofrotational movement range 338) can equal the force associated withraising first portion 46. In yet another embodiment, the amount oftorsional flexure of elastic or resilient member 68 (associated with anamount of rotational movement range 338) can exceed the force associatedwith raising first portion 46, although this construction would tend toreduce the beneficial effects the load limiting apparatus.

As further shown in FIG. 13, inner hub 350 and a sleeve 376 extend alongaxis 56 of torsion device 390. In one embodiment, sleeve 376 and innerhub 350 are of unitary or one-piece construction. An elastic orresilient member 330 is either inserted or formed between a portion 332of inside surface 366 of housing 360 and outside surface 334 of sleeve376, in which elastic or resilient member 330 (partially shown in FIG.13) forms a non-rotational contact between surfaces 366, 334 in asimilar manner as previously discussed. In one embodiment, inner hub 350may be safely positioned at one end of torsion device 390 along axis 56.In another embodiment, inner hub 350 may be located at any positionwithin or substantially within torsion device 390. In yet anotherembodiment, multiple inner hubs 350 may be located at any positionwithin or substantially within torsion device 390.

In an alternate embodiment as shown in FIG. 13, torsion device 390optionally includes a housing portion 340 that can be aligned andpositioned relative to housing 360 as shown. One having ordinary skillin the art can appreciate that a second inner hub (not shown) can beconfigured with abutting features similar as shown in FIG. 14, with theexception that the relative rotational movement between the inner huband the housing portion 340 would be opposite to that shown in FIG. 14.That is, in such a construction, abutting features between correspondinginner hubs and the inside surfaces of corresponding housing portionsdefine a movement limiting apparatus in each opposed rotationaldirection of the inner hubs relative to the corresponding housingportions.

While the invention has been described with reference to a preferredembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

What is claimed is:
 1. A system for supporting a cutterbar of a cropharvesting header comprising: a first arm pivotably secured to theheader, the first arm including a first portion configured to supportthe cutterbar, the first arm including a second portion including atorsion device having a mass of elastic material connected to anadjustment assembly, the second portion configured to be pivotablyrotatable about art axis by the adjustment assembly to selectablyincrease or decrease a force appliable to the first portion in order toraise or lower the first portion with respect to the header; a loadlimiting apparatus that prevents further torsional loading for the massof elastic material the load limiting assembly attached to the torsiondevice, the further torsional loading generated from a force equal orless than a force required to raise the first portion by pivotablerotation of the second portion about the axis, the adjustment assemblyincluding a second arm interconnecting the torsion device and anadjustment device having a first segment, the adjustment deviceconfigured to movably receive a connecting adjustment device; whereinthe first segment of the adjustment device is configured to follow apredetermined path in a first direction with respect to the axis inresponse to movement of the adjustment device in a first direction withrespect to the first adjustment device; and wherein the first segment ofthe adjustment device is configured to follow a predetermined path in asecond direction with respect to the axis in response to movement of theconnecting adjustment device in a second direction opposite the firstdirection with respect to the adjustment device.
 2. The system of claim1, wherein the axis is substantially parallel to the cutterbar.
 3. Thesystem of claim 1, wherein the load limiting apparatus limiting theamount of torsional force that is applied to the mass of elasticmaterial by pivotable rotation of the second portion about the axis isassociated with selectably increasing the force appliable to the firstportion to raise the first portion with respect to the header.
 4. Thesystem of claim 1, wherein the second portion includes the load limitingapparatus.
 5. The system of claim 1, wherein the load limiting apparatusis contained inside the torsion device.
 6. The system of claim 5,wherein the torsion device includes an inner hub rotatable relative to ahousing about the axis, the inner hub and the housing each having acorresponding abutting feature limiting the relative rotation in atleast one rotational direction about the axis.
 7. The system of claim 6,wherein in response to sufficient relative rotation in the at least onerotational direction about the axis resulting in corresponding featuresof the inner hub and the housing achieving abutting contact, additionalrotation in the at least one rotational direction about the axisresulting in the inner hub and the housing rotating about the axis inunison.
 8. The system of claim 6, wherein the abutting feature is atooth formed in each of the inner hub and the housing.
 9. The system ofclaim 6, wherein the inner hub and a sleeve extending along the axis ofthe torsion device.
 10. The system of claim 8, wherein the sleeve andthe inner hub are of unitary construction.
 11. The system of claim is 6,wherein the inner hub is positioned at one end of the torsion devicealong the axis.
 12. The system of claim is 6, wherein the inner hub ispositioned between opposed ends of the torsion device along the axis.13. A system for supporting a cutterbar of a crop harvesting headercomprising: a first arm pivotably secured to the header, the first armincluding a first portion configured to support the cutterbar, the firstarm including a second portion including a torsion device having a massof elastic material connected to an adjustment assembly, the secondportion configured to be pivotably rotatable about an axis by theadjustment assembly to selectably increase or decrease a force appliableto the first portion in order to raise or lower the first portion withrespect to the header; a load limiting apparatus as part of the torsiondevice, to prevent additional torsional loading for the mass of elasticmaterial, the additional torsional loading generated from a force inexcess of a force required to raise the first portion by pivotablerotation of the second portion about the axis; the adjustment assemblyincluding a second arm interconnecting the torsion device and anadjustment device having a first segment, the adjustment deviceconfigured to movably receive a connecting adjustment device; whereinthe first segment of the adjustment device is configured to follow apredetermined path in a first direction with respect to the axis inresponse to movement of the adjustment device in a first direction withrespect to the first adjustment device; and wherein the first segment ofthe adjustment device is configured to follow a predetermined path in asecond direction with respect to the axis in response to movement of theconnecting adjustment device in a second direction opposite the firstdirection with respect to the adjustment device.
 14. The system of claim13, wherein the load limiting apparatus limiting the amount of torsionalforce that is applied to the mass of elastic material by pivotablerotation of the second portion about the axis is associated withselectably increasing the force appliable to the first portion to raisethe first portion with respect to the header.
 15. The system of claim13, wherein the torsion device includes an inner hub rotatable relativeto a housing about the axis, the inner hub and the housing having acorresponding abutting feature limiting rotation relative to each otherin at least one rotational direction about the axis.
 16. The system ofclaim 15, wherein in response to sufficient relative rotation in the atleast one rotational direction about the axis resulting in correspondingfeatures of the inner hub and the housing achieving abutting contact,additional rotation in the at least one rotational direction about theaxis resulting in the inner hub and the housing rotating about the axisin unison.
 17. The system of claim 15, wherein the inner hub and asleeve extend along the axis of the torsion device.
 18. The system ofclaim 15, wherein the abutting feature is a tooth formed in each of theinner hub and the housing.
 19. The system of claim 15, wherein thesleeve and the inner hub are of unitary construction.
 20. The system ofclaim is 15, wherein the inner hub is positioned at one end of thetorsion device along the axis.